The cost of building a house in Pretoria with a builder who provides labour only

I have a stand that has been paid off and I am considering building a single story house with 280 square meters in pretoria. I intent to engage a builder who only provides labour and I provide the materials. I think this is a cheaper option than to engage a construction company which charges per square meter because I can shop around the building material. I would like to find out if there is anyone who has used this method when building and if anyone is aware of the costs that are involved with this type of arrangement.

If you pay the man by labour and supply the building materials,(i am assuming you are not a construction engineer or the like)
How will you prevent him from excess wastage?
How will you bargain for the best prices,as good construction companies get huge discounts and good delivery as they buy in bulk,and have a relationship with the supplier,where as you will have none and hope for sales and bargains

If you are only paying him by labour,and not for certain completions and completion dates under the contract,how will you prevent him from going excessively slow,taking longer charging you more etc

Constructor provides labour and building materials.
Will also agree that any expenses beyond the completion date will be bared against the constructor AT NOT EXPENSE to you.
Project start Date=
Completion = date you want your house done

40% completion = tiling of floor,main constructs of roof,pillars and grounding
70%= plumbing,sewerage water and electricity complete
100% full working and presentable condition,painted,cleaned,cupboards,and outter customizables complete

Thanks for the advise. I intend to employ someone on a casual basis who will be on site all the time to curb against stealing and wastage. I do not intend to employ a professional but someone that i know and trust who will not cost me more than the current minimum wages in the building sector.

I have a stand that has been paid off and I am considering building a single story house with 280 square meters in pretoria. I intent to engage a builder who only provides labour and I provide the materials. I think this is a cheaper option than to engage a construction company which charges per square meter because I can shop around the building material. I would like to find out if there is anyone who has used this method when building and if anyone is aware of the costs that are involved with this type of arrangement.

I did what you are proposing.

I got an Architect to draw up the plans and get three quotes

The Successful bidder provided a Bill Of Materials, so the wastage was controlled by the BOM.

The quote was for labour and management of the build. All materials were paid for by me, via a bond with draw off points.

I had about R250000 in available cash to get to the first draw.

Discounts are available in the form of an annual kickback from firms like Chamberlains, but I found that I could beat most of the BOM prices by shopping around.

The building contract had a penalty clause for late finish, and a bonus clause for early completion. As it happened, the build was on time.

I was able to supervise the build through three webcams, plus my wife was next door to the plot.

The costs would be out of date as this was 4 years ago.

Timing is also important, my build was from May to November, so weather did not affect things.